Home sales are often considered an important determinant of the future health of the economy. Thus, there is widespread interest in being able to forecast home sales (HS). Quarterly data for HS are shown in the following table in thousands of units.

Date	Home sales (000) Per Quarter		Date	Home sales (000) Per Quarter		Date	Home sales (000) Per Quarter
Mar-89	161		Mar-95	154		Mar-01	251
Jun-89	179		Jun-95	185		Jun-01	243
Sep-89	172		Sep-95	181		Sep-01	216
Dec-89	138		Dec-95	145		Dec-01	199
Mar-90	153		Mar-96	192		Mar-02	240
Jun-90	152		Jun-96	204		Jun-02	258
Sep-90	130		Sep-96	201		Sep-02	254
Dec-90	100		Dec-96	161		Dec-02	220
Mar-91	121		Mar-97	211		Mar-03	256
Jun-91	144		Jun-97	212		Jun-03	299
Sep-91	126		Sep-97	208		Sep-03	294
Dec-91	116		Dec-97	174		Dec-03	239
Mar-92	159		Mar-98	220		Mar-04	314
Jun-92	158		Jun-98	247		Jun-04	329
Sep-92	159		Sep-98	218		Sep-04	292
Dec-92	132		Dec-98	200		Dec-04	268
Mar-93	154		Mar-99	227		Mar-05	328
Jun-93	183		Jun-99	248		Jun-05	351
Sep-93	169		Sep-99	221		Sep-05	326
Dec-93	160		Dec-99	185		Dec-05	278
Mar-94	178		Mar-00	233		Mar-06	285
Jun-94	185		Jun-00	226		Jun-06	300
Sep-94	165		Sep-00	219		Sep-06	251
Dec-94	142		Dec-00	199		Dec-06	216
						Mar-07	214
						Jun-07	240

1. Prepare a time-series plot of THS. Describe what you see in this plot in terms of trend and seasonality.
2. Calculate and plot the first 12 auto-correlation coefficients for HS. What does this autocorrelation structure suggest about the trend?