df_by_position = df.groupby(df.position.apply(lambda x: round(x, 0))).agg({
    "clicks": "sum", "impressions": "sum"
})
df_by_position['ctr'] = (df_by_position.clicks / df_by_position.impressions)*100
df_by_position[df_by_position.index <= 20].ctr.plot(title="Click Through Rate (CTR) by Position")