As suggested, there is no built-in way to do this, so a lookup table seems the easiest way to do it. Here is the file I use for the lookup:
"date_year","date_month","date_numericmonth","day_number"
2017,january,01,31
2017,february,02,28
2017,march,03,31
2017,april,04,30
2017,may,05,31
2017,june,06,30
2017,july,07,31
2017,august,08,31
2017,september,09,30
2017,october,10,31
2017,november,11,30
2017,december,12,31
2016,january,01,31
2016,february,02,29
2016,march,03,31
2016,april,04,30
2016,may,05,31
2016,june,06,30
2016,july,07,31
2016,august,08,31
2016,september,09,30
2016,october,10,31
2016,november,11,30
2016,december,12,31
2015,january,01,31
2015,february,02,28
2015,march,03,31
2015,april,04,30
2015,may,05,31
2015,june,06,30
2015,july,07,31
2015,august,08,31
2015,september,09,30
2015,october,10,31
2015,november,11,30
2015,december,12,31
2014,january,01,31
2014,february,02,28
2014,march,03,31
2014,april,04,30
2014,may,05,31
2014,june,06,30
2014,july,07,31
2014,august,08,31
2014,september,09,30
2014,october,10,31
2014,november,11,30
2014,december,12,31
2013,january,01,31
2013,february,02,28
2013,march,03,31
2013,april,04,30
2013,may,05,31
2013,june,06,30
2013,july,07,31
2013,august,08,31
2013,september,09,30
2013,october,10,31
2013,november,11,30
2013,december,12,31
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