# Stock averaged

[edit / update model]Some appliances become more energy-efficient as technology advances, but other appliances - notably computers - now consume more energy than before.

The following example illustrates a stock average for desktop computers (without monitors) between the years 2004 and 2006.

Year | Stock in use | Energy usage kWh/year | Product |
---|---|---|---|

X | Y | X*Y | |

2004 | 20738755 | 211.16 | 4379196271 |

2005 | 21657463 | 229.68 | 4974293424 |

2006 | 22505860 | 235.18 | 5292973359 |

A | Sum of X*Y | 14646463054 | |

B | Sum of X | 64902078 | |

Stock-average | A/B | 225.67 |