问答题

1. 描述图表中生活费用支出的变化情况
2. 给出可能的原因
3. 得出你的结论

Year	1998	1991	1994	1997	2000	2002
Food	24.4%	24%	23.1%	22.3%	22%	22.2%
Medical Care	2.5%	2.5%	2.7%	2.9%	3.2%	3.2%
Transportation and Communication	10.2%	10%	10.6%	11.6%	12.8%	13.2%
Clothes	7.1%	7.1%	6.2%	5.7%	5%	4.8%
Fuel, Light and Water Charges	5.1%	5.1%	5.4%	5.8%	6.2%	6.3%