import matplotlib
matplotlib.use('TkAgg')

import matplotlib.pyplot as plt
import pandas as pd
import seaborn as sns

df = pd.read_csv('http://www.who.int/childgrowth/standards/wfa_boys_p_exp.txt', sep='\t', index_col=0)

DAYS_IN_MONTH = 30.4375
DAYS_IN_YEAR = DAYS_IN_MONTH * 12

percentile_list = []

for i in range(7):
    percentile_list.append((tuple(df.columns[[3 + i,17 - i]])))

df.index = df.reset_index()['Age'].div(DAYS_IN_MONTH)
df = df.loc[df.index < 12]

fig, ax = plt.subplots()
df['P50'].plot(ax=ax, color='w')

x = df.index

color_list = sns.color_palette("Blues", len(percentile_list))

for i, j in enumerate(percentile_list):    
    y1 = df[j[0]]
    y2 = df[j[1]]
    ax.fill_between(x, y1, y2, color=color_list[i])

text_annotations= []

for i in df.columns[3:]:
    annotation = ax.annotate(i, xy=(12, df.loc[:,i].iloc[-1]),  
                             xytext=(5,0), textcoords="offset points",
                             va="center", ha="left", size=8)
    text_annotations.append(annotation)

fig.savefig('weight_chart.png', bbox_inches='tight')
fig.savefig('weight_chart_dpi.png', bbox_inches='tight', dpi=300)