What is the Number of shares held, end of year expressed as a percentage of Number of common stock outstanding, end of year?
{"Changes in common stock: -- Number of shares, beginning of year": {"2019": 231619037, "2018": 230080944, "2017": 227638738}, "Changes in common stock: -- Restricted stock shares issued for new awards(1)": {"2019": 1478, "2018": 569960, "2017": 480283}, "Changes in common stock: -- Restricted stock shares, forfeited(1)": {"2019": -110984, "2018": -86518, "2017": -184235}, "Changes in common stock: -- Shares issued for vested restricted stock units": {"2019": 164347, "2018": 151280, "2017": 607231}, "Changes in common stock: -- Shares issued as part of acquisition(2)": {"2019": "\u2014", "2018": 20000, "2017": "\u2014"}, "Changes in common stock: -- Shares issued for 2014 Special Performance Stock Units (PSU) Awards": {"2019": "\u2014", "2018": 658783, "2017": 749653}, "Changes in common stock: -- Shares issued for 2015 Three-Year PSU Awards": {"2019": "\u2014", "2018": 129139, "2017": "\u2014"}, "Changes in common stock: -- Shares issued for 2014 Three-Year PSU Awards": {"2019": "\u2014", "2018": "\u2014", "2017": 636723}, "Changes in common stock: -- Shares issued for Stock Leverage Opportunity Awards (SLO)": {"2019": 6321, "2018": 109841, "2017": 136783}, "Changes in common stock: -- Shares granted and issued under the Omnibus Incentive Plan and Directors Stock Plan to Directors": {"2019": 123824, "2018": 10841, "2017": 15768}, "Changes in common stock: -- Canceled shares for tax netting(3)": {"2019": -181488, "2018": "\u2014", "2017": "\u2014"}, "Changes in common stock: -- Other activity(4)": {"2019": "\u2014", "2018": -25233, "2017": "\u2014"}, "Changes in common stock: -- Number of shares issued, end of year(1)": {"2019": 231622535, "2018": 231619037, "2017": 230080944}, "Changes in common stock in treasury: -- Number of shares held, beginning of year": {"2019": 75964667, "2018": 61485423, "2017": 34156355}, "Changes in common stock in treasury: -- Repurchase of common stock(5)": {"2019": 1632163, "2018": 14826924, "2017": 27320816}, "Changes in common stock in treasury: -- Profit sharing contribution paid in stock": {"2019": -487108, "2018": -538524, "2017": -502519}, "Changes in common stock in treasury: -- Shares withheld for taxes(3)": {"2019": "\u2014", "2018": 190844, "2017": 510771}, "Changes in common stock in treasury: -- Number of shares held, end of year(5)": {"2019": 77109722, "2018": 75964667, "2017": 61485423}, "Changes in common stock in treasury: -- Number of common stock outstanding, end of year": {"2019": 154512813, "2018": 155654370, "2017": 168595521}}
num_shares = df["Changes in common stock in treasury: -- Number of shares held, end of year(5)"]["2019"]
num_common_stock = df["Changes in common stock in treasury: -- Number of common stock outstanding, end of year"]["2019"]
answer = num_shares / num_common_stock * 100.0