Table 3. Frequency of behavior-related keywords

The I pericd (2000 ∼2004)		The II period (2005 ∼2009)		The III period (2010∼2014)		The IV period (2015∼2017)
Keyword	Frequency	Keyword	Frequency	Keyword	Frequency	Keyword	Frequency
	Percentage		Percentage		Percentage		Percentage
Exercise	474	Ice rink	470	Famous and delicousor tasty food are sold	840	Picnic	1178
	1.756%		1.45%		2.06%		2.58%
Take a picture	226	Picture	313	Date	453	Cafe	831
	0.84%		0.97%		1.11%		1.82%
See	130	Take a walk	219	Physical activity	415	Landscape	708
	0.48%		0.68%		1.02%		1.55%
Bicycle	78	Eat	161	Walk	389	Picture	475
	0.29%		0.50%		0.95%		1.04%
Roller skating	73	Bicycle	138	Picture	364	Show	457
	0.27%		0.43%		0.89%		1.00%
Ride	63	Ride	117	Snapshot	357	Date	370
	0.23%		0.36%		0.88%		0.81%
Walk	61	See	100	Shooting	224	Famous and delicousor tasty food are sold	354
	0.23%		0.31%		0.55%		0.78%
Take a walk	60	Show	91	Take a walk	206	Cell phone	330
	0.22%		0.28%		0.51%		0.72%
Eat	60	Landscape	90	Festival	199	Snapshot	325
	0.22%		0.28%		0.49%		0.71%
Preview	56	Art gallery	87	Run	185	Instagram (SNS)	324
	0.21%		0.27%		0.45%		0.71%