We had a particularly strong quarter, converting enterprise accounts from the straightforward annual renewals of non-consumption based models to E365 right up to the end of the year. With consumption generally rising year-over-year for existing E365 contracts, we focus on renewal negotiations for higher annual deposits, floors and caps which in many cases were not concluded until nearly year-end. The resulting later billing led to late collections, but it’s one in Q4 shortfalls was fully offset by extraordinary collections in early 2023. Our 2022 cash flows were also impacted by higher cash interest and Q4 was also unfavorable due to some significant vendor payments, which we accelerated to obtain better terms. For 2023 and prospectively, given higher interest rates and the higher cash tax burden from the requirements of the 2017 Tax Cuts and Jobs Act to now capitalize and amortize R&D expenses rather than straight expensing them, we estimate that our conversion rate of adjusted EBITDA to cash flow from operations will be approximately 80%.
Along with providing sufficiently for our growth initiatives, and our 2023 increase to a modest dividend, our capital allocation prioritizes equity and debt repurchases to offset dilution from stock-based compensation. Accordingly, against stock-based compensation of $75 million in 2022, we spent $44 million on de facto share repurchases associated mainly with deferred compensation plan distributions and under our stock repurchase program, which we announced in the second quarter, we repurchased shares for $28 million on convertible senior notes for $2 million. As of the end of December, our net debt senior leverage was 1.3 times and when including our 2026 and 2027 convertible notes as debt, our net debt leverage was 4.7 times. Approximately 80% of the debt is protected from rising interest rates through either very low fixed coupon interest of our convertible notes or our $200 million interest rate swap expiring in 2030.
And if I assume an approximately $100 million per year investment into programmatic acquisitions, which does exceed recent averages, we can expect to delever at a rate of about 0.7 times adjusted EBITDA annually. Moving to our 2023 outlook, our outlook reflects our continued margin improvement commitment of approximately 100 basis points and our continued focus to maximize our long-term ARR growth. While we continue to see unprecedented market demand for infrastructure engineering going digital, our outlook does factor in a cautious approach towards China due to continued uncertainties. Accordingly, we expect total revenue on an as-reported basis in the range of $1.205 billion to $1.235 billion, representing growth of 9.5% to 12.5%, or between 10.5% and 13.5% on a constant currency basis.
We are projecting constant currency ARR growth between 11.5% and 13.5%. We expect an adjusted operating income with stock-based compensation margin of approximately 26%, which is reflective of our 100 basis point annual margin improvement commitment. Any FX impact on our margins is significantly mitigated by our fairly effective natural hedge. We expect our effective tax rate to be approximately 20%. As I mentioned before, we expect cash flows from operations to convert from our adjusted EBITDA at the rate of approximately 80%, and we expect capital expenditures of approximately $30 million, which includes approximately $10 million of incremental IT investments into our ERP system. To help you with your models, I also include here on the slide additional expectations on interest expense and cash interest cash taxes, stock-based compensation, operating depreciation and amortization, outstanding shares and dividends.
And with that, I think we are ready for Q&A. Over to Eric to moderate. Thank you.
Eric Boyer : Great. We’ll now move to the Q&A portion of our presentation. We ask that each analyst limit themselves to one question and one follow-up. First, we’ll go to Joe Vruwink from Baird.
Joe Vruwink: Hi. Great. Can you hear me?
Eric Boyer: Yes. Go ahead, Joe.
