2000 to 2010
deficit is when the money spent is larger than the money received.
for our graph, the period where orange line is above the blue line.
looking at the whole graph, around 2006-07 to 2010, the money spent is around 1.5 trillion usd above money received.
so looking at the period 2000 - 2010, the deficit will be the largest in this due to the big gap (deficit) around 2006-07 - 2010 years.
note: the other periods does have deficit but the amount is not that much.
here's why :
in order to measure qualitative data quantitively, categorical variables are used. these type of variables are defined by a set of positive numbers, and each number is connected to a nominal category, which has been defined based on a qualitative property.
for example, if conducting a research about holiday patterns, one of the variables registered aims to measure the season in which people travel the most hence the following categories are defined: spring (=1), summer (=2), autumn (=3) and winter (=4). this is a categorical variable. if it only had two categories it is denominated a dummy or binary variable (values: 0, 1).