According to ISTAT, in 2014 there were 154,356 people residing in Cagliari (+3.0% compared with 2011), of whom 71,522 were male and 82,834 female for a sex ratio of 0.86. Minors (children aged 18 and younger) totalled 12.92% of the population, compared to pensioners at 24.81%. The average age of Cagliari residents is 47.44. The ratio of the population over 65 years of age to that under the age of 18, is 53.39%. The elderly population, defined as being over 65 years of age, has increased by 21.95% over the last 10 years. The current birth rate in Cagliari is 6.29 births per 1,000 inhabitants. The average number of people of any age per household is 2.11 and the percentage of households composed of a single person is 42.53%. The population of Cagliari is structured like that of other first world countries, especially as to the prevalence of an elderly population. The trend of these rates in the Cagliari metropolitan area is proportionally reversed in the suburbs, where most younger families move.
Question: Which ratio is the lowest in Caligari, residents or births?
Answer: births