Life expectancy by birth is estimated to 57.5 years. Public expenditure on health was at 2.4 percent of the GDP in 2004, whereas private expenditure was at 3.5 percent. Health expenditure was at US$72 (PPP) per capita in 2004. The fertility rate ranged 5 to 5.3 between 2005 and 2013, with 4.1 in urban areas and 6.3 in rural areas, as official survey (6.4 in 1986 and 5.7 in 1997) point out. There were six physicians per 100,000 persons in the early 2000s (decade). Infant mortality was at 77 per 1,000 live births in 2005, but in 2013 this figure had dropped to 47 within the first 12 months after birth. In the past 5 years infant mortality rates of malaria have dropped. According to a 2013 UNICEF report, 26% of women in Senegal have undergone female genital mutilation.
Question: How many births did the infant mortality rate drop by from 2005 to 2013?
Answer: 30