new_df['year'].describe()
count 10866.000000
mean 2004.009939
std 14.958790
min 1968.000000
25% 1996.000000
50% 2006.000000
75% 2012.000000
max 2067.000000
Name: year, dtype: float64
It seems like the erroneous year values are +100 years off (ie, 2067 should probably be 1967). Therefore, for values above 2018, how do I [year - 100] while leaving the rest of the values untouched?