Direction: The following table shows production of cars (in thousands) in a Company from 1999 to 2004. Study the table and answer the questions

Year	1999	2000	2001	2002	2003	2004
Type
P	8	20	16	17	21	6
Q	16	10	14	12	12	14
R	21	17	16	15	13	8
S	4	6	10	16	20	31
T	25	18	19	30	14	27
Total	74	71	75	90	80	86

In which year, the total production of cars of types P and Q together was equal to the total production of cars of types R and S together?