## 4 Temporal and Spatial Characteristics  
### General Characteristic Analysis  
The results are shown in Figure 2. The results show that the number of employees in the producer service industry showed a gradual growth trend and achieved leap-forward growth in 2012-2013 and 2018-2019. Specifically, in 2010, the number of employees was 18.86 million, accounting for 13.78%. By 2019, the number of employed people in the producer service industry had increased to 31.83 million, accounting for 18.60%, which is close to one-fifth of the national total. Among them, in 2012-2013 and 2018-2019, the number of employees increased by 4.79 and 3.04 million, respectively, and the growth rate reached 23.52% and 10.57%, which exceeded other historical growth levels.  
In terms of industries, the transportation-related industry has the highest employment share, with an average value of 31.19% over the years. The average employment proportions of the rest of the industries were 23.99%, 17.16%, 15.04%, and 12.62%, respectively. From the perspective of the changing trend, the employment share of the transportation-related industry dropped significantly. In contrast, the proportion of employees of information and service industries continued to increase, rising from 8.93% to 14.27% and 16.43% to 20.69%, respectively [10].  
With the help of ArcGIS 10.6, a comparative analysis of the 30 provincial units in the producer service industry was performed to systematically analyze the evolution characteristics of the pattern. The number of employees in the producer service industry is divided into five levels from low to high, namely the first level (0, 40), the second level (40, 80), the third level (80, 130), the fourth level (130, 240), and the fifth level (240, 400). The results are shown in Figure 3. The inter-provincial differences are obvious and continue to expand. Further, the pattern presents high in the east and low in the central and western regions. Moreover, the number of employees in each provincial unit has increased to varying degrees over time, among which, the eastern part increased significantly and accounted for a relatively high proportion, and the central and western regions increased slowly and accounted for a relatively low proportion.  
Figure 2: The structure of the producer service industry and its sub-industry.  
Furthermore, the producer service industry agglomeration index is also divided into five levels, which are low agglomeration level (0, 0.8), lower agglomeration level (0.8, 1), general agglomeration level (1, 1.2), higher agglomeration level (1.2, 1.5), and high agglomeration levels (1.5, 2.8), and the results are shown in Figure 4. It also shows significant inter-provincial differences, but the overall difference is shrinking. It presents a pattern of high in the east and low in the central and western regions. However, compared with the number of employments in the producer service industry, the first feature of the agglomeration index is more obvious, as it fell to a lower level of agglomeration. Heilongjiang in the central part and Hainan in the east showed a gradual rise, reaching a higher level of agglomeration and a general level of agglomeration.