You are now a sqlite data analyst, and you are given a database schema as follows:

    【Schema】
    【DB_ID】 superstore
【Schema】
# Table: south_superstore
[
(Row ID:INTEGER, Primary Key, Examples: [10343, 10344, 10345]),
(Order ID:TEXT, Examples: [CA-2011-106054, CA-2011-167199, CA-2011-149020]),
(Order Date:DATE, Examples: [2013-01-06]),
(Ship Date:DATE, Examples: [2013-01-07]),
(Ship Mode:TEXT, Examples: [First Class, Standard Class, Second Class]),
(Customer ID:TEXT, Examples: [JO-15145, ME-17320, AJ-10780]),
(Region:TEXT, Examples: [South]),
(Product ID:TEXT, Examples: [OFF-AR-10002399, FUR-CH-10004063, OFF-BI-10004632]),
(Sales:REAL, Examples: [12.78, 2573.82, 609.98]),
(Quantity:INTEGER, Examples: [3, 9, 2]),
(Discount:REAL, Examples: [0.0, 0.7, 0.2]),
(Profit:REAL, Examples: [5.2398, 746.4078, 274.491])
]
# Table: people
[
(Customer ID:TEXT, Primary Key, Examples: [AA-10315, AA-10375, AA-10480]),
(Customer Name:TEXT, Examples: [Alex Avila, Allen Armold, Andrew Allen]),
(Segment:TEXT, Examples: [Consumer, Home Office, Corporate]),
(Country:TEXT, Examples: [United States]),
(City:TEXT, Examples: [Round Rock, Omaha, Springfield]),
(State:TEXT, Examples: [Texas, Nebraska, Missouri]),
(Postal Code:INTEGER, Examples: [78664, 68104, 65807]),
(Region:TEXT, Primary Key, Examples: [Central, East, West])
]
# Table: west_superstore
[
(Row ID:INTEGER, Primary Key, Examples: [13583, 13584, 13585]),
(Order ID:TEXT, Examples: [CA-2011-130813, CA-2011-157147, CA-2011-123477]),
(Order Date:DATE, Examples: [2013-01-06]),
(Ship Date:DATE, Examples: [2013-01-08]),
(Ship Mode:TEXT, Examples: [Second Class, Standard Class, First Class]),
(Customer ID:TEXT, Examples: [LS-17230, BD-11605, DW-13195]),
(Region:TEXT, Examples: [West]),
(Product ID:TEXT, Examples: [OFF-PA-10002005, OFF-ST-10000078, FUR-BO-10003034]),
(Sales:REAL, Examples: [19.44, 1325.85, 333.999]),
(Quantity:INTEGER, Examples: [3, 5, 4]),
(Discount:REAL, Examples: [0.0, 0.15, 0.2]),
(Profit:REAL, Examples: [9.3312, 238.653, 3.9294])
]
# Table: east_superstore
[
(Row ID:INTEGER, Primary Key, Examples: [4647, 4648, 4649]),
(Order ID:TEXT, Examples: [CA-2011-141817, CA-2011-130092, CA-2011-118192]),
(Order Date:DATE, Examples: [2013-01-05]),
(Ship Date:DATE, Examples: [2013-01-12]),
(Ship Mode:TEXT, Examples: [Standard Class, First Class, Second Class]),
(Customer ID:TEXT, Examples: [MB-18085, SV-20365, MM-17920]),
(Region:TEXT, Examples: [East]),
(Product ID:TEXT, Examples: [OFF-AR-10003478, FUR-FU-10000010, OFF-PA-10002947]),
(Sales:REAL, Examples: [19.536, 9.94, 37.408]),
(Quantity:INTEGER, Examples: [3, 2, 7]),
(Discount:REAL, Examples: [0.2, 0.0, 0.7]),
(Profit:REAL, Examples: [4.884, 3.0814, 13.0928])
]
# Table: central_superstore
[
(Row ID:INTEGER, Primary Key, Examples: [1, 2, 3]),
(Order ID:TEXT, Examples: [CA-2011-103800, CA-2011-112326, CA-2011-105417]),
(Order Date:DATE, Examples: [2013-01-03]),
(Ship Date:DATE, Examples: [2013-01-07]),
(Ship Mode:TEXT, Examples: [Standard Class, First Class, Second Class]),
(Customer ID:TEXT, Examples: [DP-13000, PO-19195, VS-21820]),
(Region:TEXT, Examples: [Central]),
(Product ID:TEXT, Examples: [OFF-PA-10000174, OFF-LA-10003223, OFF-ST-10002743]),
(Sales:REAL, Examples: [16.448, 11.784, 272.736]),
(Quantity:INTEGER, Examples: [2, 3, 7]),
(Discount:REAL, Examples: [0.2, 0.8, 0.6]),
(Profit:REAL, Examples: [5.5512, 4.2717, -64.7748])
]
# Table: product
[
(Product ID:TEXT, Primary Key, Examples: [FUR-BO-10000112, FUR-BO-10000330, FUR-BO-10000362]),
(Product Name:TEXT),
(Category:TEXT, Examples: [Furniture, Office Supplies, Technology]),
(Sub-Category:TEXT, Examples: [Bookcases, Chairs, Furnishings]),
(Region:TEXT, Primary Key, Examples: [Central, South, West])
]
【Foreign keys】
south_superstore.Customer ID=people.Customer ID
south_superstore.Region=people.Region
south_superstore.Product ID=product.Product ID
south_superstore.Region=product.Region
west_superstore.Customer ID=people.Customer ID
west_superstore.Region=people.Region
west_superstore.Product ID=product.Product ID
west_superstore.Region=product.Region
east_superstore.Customer ID=people.Customer ID
east_superstore.Region=people.Region
east_superstore.Product ID=product.Product ID
east_superstore.Region=product.Region
central_superstore.Customer ID=people.Customer ID
central_superstore.Region=people.Region
central_superstore.Product ID=product.Product ID
central_superstore.Region=product.Region

    【Question】
    What percentage do items under the category of 'Furniture' make up the total number of items ordered that are shipped as standard in the West region? shipped as standard refers to "Ship Mode" = 'Standard Class'; Region = 'West'; percentage refers to DIVIDE(SUM(Quantity where Category = 'Furniture'), SUM(Quantity)) * 1.0

    【Evidence】
    shipped as standard refers to "Ship Mode" = 'Standard Class'; Region = 'West'; percentage refers to DIVIDE(SUM(Quantity where Category = 'Furniture'), SUM(Quantity)) * 1.0

    Please read and understand the database schema carefully, and generate an executable SQL based on the user's question and evidence. 

SQL: SELECT CAST(SUM(CASE  WHEN T2.Category = 'Furniture' THEN 1 ELSE 0 END) AS REAL) * 100 / SUM(T1.Quantity) FROM west_superstore AS T1 INNER JOIN product AS T2 ON T1.`Product ID` = T2.`Product ID` WHERE T2.Region = 'West' AND T1.`Ship Mode` = 'Standard Class'