+----------------------------------------------+
 | DATE     ID     USERNAME       CREDITS       |
 +----------------------------------------------+
 | ...      1         X              12         |
 | ...      2         E               2         |
 | ...      3         F               8         |
 | ...      4         E               2         |

 [ .... many, many other records where USERNAME is not 'X'

 | ...      302       X               1         |

 [ .... many, many other records where USERNAME is not 'X'

 | ...      804       X              -7         |

 [ .... many, many other records where USERNAME is not 'X'

 | ...      1502      X               4         |
 +----------------------------------------------+