[Retracted] Emergency Management System for Coal Mine Safety Based on IoT Technology

Table 5

Comparison of coal networking level (input).

Time (year)	2012	2013	2014	2015	2016	2017
Strategy 2	5	18.2	32.9	48.25	61.93	73.58
Strategy 1	5	16.84	29.67	41.87	52.08	61.98
Initial	5	12.23	21.51	30.07	39.71	49.25