variable <- c("Revenue", "Cost of Goods Sold", "Gross Profit", "SG&A", "Operating Income", "Interest Expense",
          "Pretax Income", "Income Tax", "Net Income")
year_2014 <- c(6500, 3012, 3488, 1231, 2257, 231, 2026, 462, 1564)
year_2015 <- c(3250, 1323, 1927, 912, 1015, 109, 906, 209, 697)
year_2016 <- c(4965, 2723, 2242, 1159, 1083, 106, 977, 187, 790)
df <- data.frame(variable, year_2014, year_2015, year_2016)

df <- df %>%
    mutate(percentage = year_2014/filter(select(year_2014), variable == "Revenue")

df <- df %>%
    mutate(percentage = year_2014/variable["Revenue"])