View source for 12. How does technoloyg affect transportation and communication which are important factors for international trad?

Accodring to a survey done by IMF, the cost of transportation and communication has dropped dramatically from 1920 to 1990 as illustrated below.
<center><table border=2 cellpadding=3 cellspacing=2>

<tr><th>Year</th><th>Sea <i>(a)</i></th><th>Air <i>(b)</i></th><th>Phone Call<br><i>(c)</i></th><th>Computers<br> <i>(d)</i></th></tr>  
<tr><th>1920</th><td align=right>95</td><td align=right>-</td><td align=right>-</td><td align=right>-</td></tr>  
<tr><th>1930</th><td align=right>60</td><td align=right>0.68</td><td align=right>245</td><td align=right>-</td></tr>  
<tr><th>1940</th><td align=right>63</td><td align=right>0.46</td><td align=right>189</td><td align=right>-</td></tr>  
<tr><th>1950</th><td align=right>34</td><td align=right>0.30</td><td align=right>53</td><td align=right>-</td></tr>  
<tr><th>1960</th><td align=right>27</td><td align=right>0.24</td><td align=right>46</td><td align=right>12,500</td></tr>  
<tr><th>1970</th><td align=right>27</td><td align=right>0.16</td><td align=right>32</td><td align=right>1,947</td></tr>  
<tr><th>1980</th><td align=right>24</td><td align=right>0.10</td><td align=right>5</td><td align=right>362</td></tr>  
<tr><th>1990</th><td align=right>29</td><td align=right>0.11</td><td align=right>3</td><td align=right>100</td></tr>  


</table><br>
</center>
(a) average ocean freight and port charges per ton ($US)<br>
(b) average revenue per passenger mile ($US)<br>
(c) 3 minutes NY/London ($US)<br>
(d) index, 1990=100<br>