<Table> <Tr> <Th_colspan="2"> Houston Rockets </Th> </Tr> <Tr> <Td_colspan="2"> <Table> <Tr> <Td> </Td> <Td> 2018--19 Houston Rockets season </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td_colspan="2"> </Td> </Tr> <Tr> <Th> Conference </Th> <Td> Western </Td> </Tr> <Tr> <Th> Division </Th> <Td> Southwest </Td> </Tr> <Tr> <Th> Founded </Th> <Td> 1967 </Td> </Tr> <Tr> <Th> History </Th> <Td> San Diego Rockets 1967--1971 Houston Rockets 1971--present </Td> </Tr> <Tr> <Th> Arena </Th> <Td> Toyota Center </Td> </Tr> <Tr> <Th> Location </Th> <Td> Houston, Texas </Td> </Tr> <Tr> <Th> Team colors </Th> <Td> Red, silver, black, white </Td> </Tr> <Tr> <Th> General manager </Th> <Td> Daryl Morey </Td> </Tr> <Tr> <Th> Head coach </Th> <Td> Mike D'Antoni </Td> </Tr> <Tr> <Th> Ownership </Th> <Td> Tilman Fertitta </Td> </Tr> <Tr> <Th> Affiliation (s) </Th> <Td> Rio Grande Valley Vipers </Td> </Tr> <Tr> <Th> Championships </Th> <Td> 2 (1994, 1995) </Td> </Tr> <Tr> <Th> Conference titles </Th> <Td> 4 (1981, 1986, 1994, 1995) </Td> </Tr> <Tr> <Th> Division titles </Th> <Td> 6 (1977, 1986, 1993, 1994, 2015, 2018) </Td> </Tr> <Tr> <Th> Retired numbers </Th> <Td> 7 (11, 22, 23, 24, 34, 45, CD) </Td> </Tr> <Tr> <Th> Website </Th> <Td> www.nba.com/rockets </Td> </Tr> <Tr> <Td_colspan="2"> </Td> </Tr> <Tr> <Td_colspan="2"> <Table> <Tr> <Td> Home </Td> <Td> Away </Td> </Tr> <Tr> <Td> Third </Td> <Td> Fourth </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td_colspan="2"> </Td> </Tr> </Table> <Tr> <Th_colspan="2"> Houston Rockets </Th> </Tr>

How many nba championships have the houston rockets won