When referring to the year 2019, Americans typically use the phrase "twenty-nineteen." This is because American dates follow the ordinal system, which assigns a number value to each month of the year: January is 1 and December is 12. As such, "twenty-nine nineteen" would be interpreted as February 29th, March 19th, and so on. In British English, "nineteen ninety-nine" would be understood as referring to 1999 rather than 2019. This is because the British date system does not have a month 0; instead there are 12 months in a year. Thus, "nineteen ninety-nine" would be interpreted as February 28th, March 18th, and so on. In Australian English, "nineteen ninety-nine" would be interpreted as referring to 2019 because there are still only 30 days in an ordinary year. However, if "ordinary years" were replaced with "leap years," then "nineteen ninety-nine" would be interpreted as 2000 due to the addition of a 31st day in a leap year.