human
table of contents valero energy corporation notes to consolidated financial statements (continued) 11. equity share activity activity in the number of shares of common stock and treasury stock was as follows (in millions): common treasury.
|  | CommonStock | TreasuryStock |
| --------- | --------- | --------- |
| Balance as of December 31, 2015 | 673 | (200) |
| Transactions in connection withstock-based compensation plans | — | 1 |
| Stock purchases under purchase program | — | (23) |
| Balance as of December 31, 2016 | 673 | (222) |
| Transactions in connection withstock-based compensation plans | — | 1 |
| Stock purchases under purchase programs | — | (19) |
| Balance as of December 31, 2017 | 673 | (240) |
| Stock purchases under purchase programs | — | (16) |
| Balance as of December 31, 2018 | 673 | (256) |
preferred stock we have 20 million shares of preferred stock authorized with a par value of $0.01 per share. no shares of preferred stock were outstanding as of december 31, 2018 or 2017. treasury stock we purchase shares of our common stock as authorized under our common stock purchase program (described below) and to meet our obligations under employee stock-based compensation plans. on july 13, 2015, our board of directors authorized us to purchase $2.5 billion of our outstanding common stock with no expiration date, and we completed that program during 2017. on september 21, 2016, our board of directors authorized our purchase of up to an additional $2.5 billion with no expiration date, and we completed that program during 2018. on january 23, 2018, our board of directors authorized our purchase of up to an additional $2.5 billion (the 2018 program) with no expiration date. during the years ended december 31, 2018, 2017, and 2016, we purchased $1.5 billion, $1.3 billion, and $1.3 billion, respectively, of our common stock under our programs. as of december 31, 2018, we have approval under the 2018 program to purchase approximately $2.2 billion of our common stock. common stock dividends on january 24, 2019, our board of directors declared a quarterly cash dividend of $0.90 per common share payable on march 5, 2019 to holders of record at the close of business on february 13, 2019. valero energy partners lp units on september 16, 2016, vlp entered into an equity distribution agreement pursuant to which vlp offered and sold from time to time their common units having an aggregate offering price of up to $350 million based on amounts, at prices, and on terms determined by market conditions and other factors at the time of.
Please answer the following questions with expressions if necessary.
what was the sum spent on common stock repurchases in 2018 and 2017?
assistant
add(1.5, 1.3)
human
what was the amount spent in 2016?
assistant
1.3
human
what is the total sum?
assistant
add(1.5, 1.3), add(#0, 1.3)