Update README.md

README.md

@@ -17,9 +17,33 @@ The container makes available a MariaDB instance with the full database on sea a
 
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 ## Specifications
+```
+Table            |Size (MB)|Rows (#)|
+-----------------+---------+--------+
+eu_ports_2009_geo|     0.30|    2201|
+eu_ports_2013_geo|     0.34|    2440|
+eu_tonnage       |     0.58|   10675|
+geometry_columns |     0.02|       3|
+spatial_ref_sys  |     0.02|       2|
+us_ports_geo     |     0.05|     150|
+```
+
+![tables schema](FACT_air.png "Tables")
 
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 ## Notes
+**Europe**
+Ports, worldwide but US not well covered.
+https://ec.europa.eu/eurostat/web/gisco/geodata/reference-data/transport-networks
+Use field PORT_ID for identification.
+
+Tonnage (in thousand tonnes, quarterly, total values)
+https://ec.europa.eu/eurostat/databrowser/view/mar_go_qm/default/table?lang=en
+
+**US**
+Principal Ports,
+The Principal Port dataset contains port codes, port names, geographic locations (longitude, latitude), and commodity tonnage summaries (total tons, domestic, foreign, imports and exports).
+https://geodata.bts.gov/datasets/usdot::principal-ports/about
 
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 ### Authors