Example 1:
Weight of students (males and females) in a university course (kg):

 

 

Example 2:
Percentages of deaths in Italy in various years:

1880-1891: from 0 to 1: 10%, from 1 to 2.6: 15%, from 2.6 to 7.6: 25%, from 7.6 to 57.7: 25%, from 57.7 to 73.8: 15%, from 73.8 to 100: 10%
...
2006: from 0 to 64.4: 10%, from 64.4 to 75.5: 15%, from 75.5 to 83.9: 25%, from 83.9 to 90.2: 25%, from 90.2 to 94.8: 15%, from 94.8 to 110: 10%