Investment income increased to $1.6 million in 2017, compared with $1.5 million in 2016 and increased to $1.5 million in 2016, compared with $1.0 million in 2015. The increases in both years are due to additional interest income driven by higher average invested cash balances accompanied by higher effective earned rates of interest.
For the years ended December 31, 2017, 2016 and 2015, the fair value of estimated earn-out payables was re-evaluated and increased by $6.9 million, $6.3 million and $13.0 thousand, respectively, which resulted in charges to the Consolidated Statement of Income.
Income before income taxes for 2016 increased 3.3%, or $6.1 million, over the same period in 2015, to $188.0 million. This growth in income before income taxes was negatively impacted by $10.3 million in expense associated with the change in estimated acquisition earn-out payables, an increase of $8.2 million over the same period in 2015. Other factors affecting this increase were: (i) the net increase in revenue as described above, (ii) a 6.3%, or $29.0 million increase in employee compensation and benefits due primarily to the year-on-year impact of new teammates related to acquisitions completed in the past twelve months and to a lesser extent continued investment in producers and other staff to support current and future expected organic revenue growth, and (iii) operating expenses which increased by $8.8 million, or 6.4%, primarily due to increased value-added consulting services to support our customers and increases in office rent expense, offset by a combined decrease in amortization, depreciation and intercompany interest expense of $4.9 million.
Income before income taxes for 2017 increased 19.8%, or $18.2 million, from the same period in 2016, to $110.0 million. The increase is the result of a lower intercompany interest charge of $10.2 million, along with leveraging revenue growth of $31.3 million.
Financial information relating to our Wholesale Brokerage Segment is as follows:
then discounted to present value using a risk-adjusted rate that takes into consideration the likelihood that the forecasted earn-out payments will be made.
Cash paid for acquisitions was $41.5 million and $124.7 million in the years ended December 31, 2017 and 2016, respectively. We completed eleven acquisitions (excluding book of business purchases) during the year ended December 31, 2017. We completed eight acquisitions (excluding book of business purchases) during the year ended December 31, 2016.
At December 31, 2017, investments with a fair value of approximately $4.1 million were on deposit with state insurance departments to satisfy regulatory requirements.
The total fair value of PSP grants that vested during each of the years ended December 31, 2017, 2016 and 2015 was $6.3 million, $18.1 million and $6.8 million, respectively.
The following table sets forth information as of December 31, 2017, 2016 and 2015, with respect to the number of time-based restricted shares granted and awarded, the number of performance-based restricted shares granted, and the number of performance-based restricted shares awarded under our Performance Stock Plan and 2010 Stock Incentive Plan:
On November 14, 2017, the Company entered into an ASR with an investment bank to purchase an aggregate $75.0 million of the Company's common stock. As part of the ASR, the company received an initial delivery of 1,290,486 shares of the Company's common stock with a fair market value of approximately $63.8 million. Upon maturity of the program, the Company received 168,227 shares, relieving the remaining balance of $11.2 million at settlement on February 9, 2018 for a total delivery of 1,458,713 shares of the Company's common stock.