Table:
text: Ghostbusters (franchise)
Other media and merchandise
Video games
Year_ Title System_ Developer Publisher_
1984 Ghostbusters Atari 800, Commodore 64, MSX, ZX Spectrum, Amstrad CPC Activision Activision
1985 Ghostbusters Atari 2600, Apple II Activision Activision
1987 The Real Ghostbusters Arcade Data East Data East
1987 Ghostbusters Sega Master System Activision Sega
1988 Ghostbusters NES Bits Laboratory Activision/Tokuma Shoten
1989 The Real Ghostbusters Commodore 64, Amiga, ZX Spectrum, Amstrad CPC, Atari ST Data East Activision
1989 Ghostbusters II Atari 2600, Amiga, Commodore 64, MSX, PC, ZX Spectrum, Amstrad CPC Activision Activision
1990 Ghostbusters II NES Kemco Activision
1990 Ghostbusters Sega Mega Drive/Genesis Sega Sega
1990 New Ghostbusters 2 Game Boy, NES Hal Laboratory Activision

Question: How many Ghostbusters games were released for the franchise in 1990?